BENEFICIAL EFFECT OF NEBRACETAM ON ENERGY-METABOLISM AFTER MICROSPHERE-INDUCED EMBOLISM IN RAT-BRAIN

The present study was undertaken to examine the possible therapeutic e ffects of nebracetam on the energy metabolism of rat brain regions in microsphere-induced, sustained ischemia. Microsphere embolism was indu ced by injection of 900 microspheres (48 mu m in diameter) into the ri ght internal carotid artery of rats, and changes in the energy metabol ism of the cerebral cortex, striatum and hippocampus of the right hemi sphere were determined without and with nebracetam treatment. Microsph ere embolism induced increases in lactate and glucose contents and dec reases of ATP and creatine phosphate contents in these regions, sugges ting that sustained impairment of cerebral energy metabolism occurred. These changes were gradually reversed with time after the operation. Treatment of microsphere-injected rats with 30 mg/kg of nebracetam, p. o., twice a day, was started one day after the onset of cerebral ische mia. The effects of treatment with nebracetam on cerebral energy metab olites were determined on the 3rd and 7th day after operation. Treatme nt of microsphere-injected rats with nebracetam significantly improved these variables on the 3rd day after the onset of ischemia, but the i mprovement was small on the 7th day, except for reversal of the hippoc ampal ATP content. These results suggest that nebracetam is a possible therapeutic agent for the restoration of cerebral energy metabolism a gainst microsphere-induced, sustained cerebral ischemia.